Pain and depression are the most common physical and psychological symptoms presenting in medical clinical practice. Indeed, they are ubiquitous across most medical and psychiatric diseases. Both pain and depression are often inadequately treated and result in substantial disability, reduced health-related quality of life, and increased health care costs and utilization. Moreover, they co-occur in up to half of patients and have reciprocal negative effects on treatment response. In contrast to many diseases, physical examination and laboratory/imaging studies have a limited diagnostic role in the assessment of pain and depression. Instead the criterion for assessing both pain and depression is self report from an individual, making the validation of patient-reported measures of pain and depression critical to both research and clinical care. In this study, PROMIS pain and depression measures will be added to 4 large studies (3 randomized clinical trials and 1 cohort study) which are beginning subject enrollment in 2012. The sample size for our proposed study will total 900 patients, ranging from 200-250 patients from each of the 4 studies. Two of the studies will be enrolling primary care patients with chronic musculoskeletal pain and two studies will be enrolling specialty clinic patients with neurologic disorders (stroke survivors and patients with mild traumatic brain injury). In each study, the PROMIS measures as well as non-PROMIS pain and depression scales (the PHQ-9 depression scale and the Brief Pain Inventory used to assist in validating the PROMIS scales) and other validating items will be added to baseline and 3-month follow-up assessments of study participants. The PROMIS measures will include all items from the PROMIS pain and depression Short Forms and Profiles. The primary aims of our ancillary study will be to perform clinically-relevant validation of the PROMIS fixed-length pain and depression scales in clinical populations by (1) assessing responsiveness and sensitivity to change, (2) establishing clinical interpretations including developing minimally important differences (MIDs), and (3) assessing the diagnostic operating characteristics of the PROMIS depression scales for detecting gold standard depressive disorder diagnoses obtained from the mood module of the Structured Clinical Interview to Diagnose DSM-IV Axis I Disorders (SCID). For sensitivity to change, we will use data from all 4 studies to evaluate the ability of PROMIS scales to differentiate between subgroups of patients in whom pain or depression has improved, remained unchanged, or worsened over time. The 3 randomized clinical trials will also be used to examine between-group (intervention vs. control) intervention effects for responsiveness to treatment. For MIDs, we will triangulate data from anchor-based and distribution-based methods using a Delphi process that will include two 9-member expert panels (1 for depression and 1 for pain). Our study findings will greatly increase the utility and incorporation of PROMIS pain and depression measures into clinical practice as well as translational research. Likewise, the meaningful interpretation of PROMIS scores will be substantially enhanced. PUBLIC HEALTH RELVANCE: Pain and depression are exceedingly common yet under evaluated and consequently, often inadequately treated, resulting in substantial disability, reduced health-related quality of life, and increased health care costs and utilization. NIH-funded PROMIS pain and depression measures hold the potential to improve evaluation of these conditions but do not have demonstrated validity in longitudinal studies of clinic populations. If shown to be sensitive, responsive, and diagnostically accurate in clinical populations, these brief and feasible tools promise to improve evaluation of pain and depression, and accordingly, reduce patients' disability and healthcare utilization and increase their quality of life.